Generally a hair folical has gotten blocked and infected. It could potentially be an cyst or hernia or a lymph node that has gotten inflammed. Scar tissue build up is another possibility. If there is pain, redness, swelling or begins to feel hot to the touch it's time to get into the doctor.

There are a couple of reasons why you might have a lump there. The first and easiest one being, it could be razor burn. Secondly, the lump could also be an ingrown hair. If you are still uncertain, you should get it checked out with your doctor.

There is not enough information here to answer this question however a lump in the pelvic area is something you might want to call and talk with your doctor about it could be a swollen lymph node which is a sign of some type of infection going on or something else.